It is all fake
Unlike a documentary, when you film a motion picture, it is all fake.
Don't try to make it real. Move the actors and/or the movie set to get the shots that you need. Don't worry if the setups is not real. Nothing is sacred!
Below are examples of getting an over-the-shoulder shot. To get the shots to look correct, the actors are in very unnatural position.
- With a strong telephoto lens, the actors might be very far apart. The two actors might not even be in the same room.
- With a strong wide angle lens, the two actors might be standing on each other shoes they are so close together.
But that is what is necessary to get the shot. So that is what you do!